<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0 ;
            padding: 0;
        }
         a{
             text-decoration: none;
         }
        ul {
            list-style: none;
        }
        .box {
            width: 200px;
            height: 400px;
            margin: 0 auto;
        }
        .son {
            width: 80px;
            
        }
         .header{
             display: block;
             width: 80px;
             height: 50px;
             color: #333;
             text-align: center;
             line-height: 50px;
             font-style: italic;
         }
         ul {
            box-shadow: 3px 3px 3px rgba(0, 0, 0, .1) ;
         }

        ul  li {
             box-sizing: border-box;
            width: 80px;
             height: 30px; 
             text-align: center;
             line-height: 30px;
             border: 1px solid orange;
             border-top: none;
             
         }

    </style>
</head>
<body>
    <div class="box">
          <div  class="son">
              <a href="#" class="header">微博</a>
              
        
              <ul style="display: none;" id="menu" class="menu_1">
                  <li>1</li>
                  <li>2</li>
                  <li>3</li>
              </ul>
            </div>
         
    </div>
    <script>
        var son = document.querySelector('.son')
        var hed = document.querySelector('.header')
      
        var menu = document.querySelector('#menu')
         son.onmouseover = function(){
             hed.style.backgroundColor = '#ccc';
                menu.style.display = 'block'
         }
         son.onmouseout = function(){
            hed.style.backgroundColor = '';
            menu.style.display = 'none'
         }
         hed.onmouseover = function(){
             this.style.color = 'red';
                
         }
         hed.onmouseout = function(){
             this.style.color = '';
                
         }
    </script>
</body>
</html>